Marine systems require rugged-duty fans for the proper ventilation of spaces below a ship's decks. Combustion blowers for the ship's boilers also require a source of fresh air. Passenger vessels and offshore platforms require higher rates of ventilation for personnel and safety reasons. NYB direct-drive axial fans are usually favored in these applications due to space-saving features. Special marine-duty electrical connections and IEEE45 motors are required. Military requirements add additional features to these special fans.